Fiber optic couplers are typically used to apply modulated light to an optical fiber from an emitting source and to apply light received from the fiber to a detecting element. Such couplers can also be used to multiplex or demultiplex modulated light carried or to be carried by an optical fiber. See my copending commonly assigned application, Ser. No. 444,494, filed Nov. 24, 1982.
Such couplers are likely to be used in great numbers and it is accordingly desirable that a coupler be capable of high volume, low cost production with a minimum of production steps and reliable construction. Such couplers must also function in environments of varying temperatures and other effects which can impact the optical properties or alignment of the coupler with detrimental effects on the coupling function.
Great positional accuracy is required in the placement of coupler elements to insure low losses in coupling light between fiber terminations and emitters and detectors. Injection molding techniques can be used for this purpose, but often are complicated by the need for side actions to accommodate all the pockets of a coupler mold. A coupler which can avoid side action molds is therefore desirable.
Optical properties which permit focussing, beam splitting or correction of spherical aberration and coma are also desired in the coupler for minimizing losses or providing flexibility in use.